Livestock and poultry in confined feeding operations produce 52 million tons of manure each year; these animal wastes pose pollution, odor and health problems. An efficient way of disposing the waste is to combust it directly and to supply the energy requirements of feed processing and power production. Manure ash has, however, shown to result in sintering and slagging of the combustor, fouling of the heat transfer surfaces and corrosion of the construction material. The sintering and fouling problems are caused mainly by relatively high mineral content of alkaline compounds (Na, K) which together with chloride (Cl) results also in high and low temperature corrosion.
The direct combustion of low-grade fuels, such as lignite or brown coal, is becoming more important for both utility and industrial use. Some of the major difficulties in burning low-grade fuels are: the fouling/slagging of the heat transfer surface and the sensitivity of the combustors to fuel variability (moisture, alkaline contents, etc.).